MacIntyre, 30, had been back with the AHL's Toronto Marlies since Bernier returned from a five-game absence with a groin injury March 25.
Bernier left Thursday night's 4-3 overtime win over the Boston Bruins with what looked like a left leg or knee injury. Asked if Bernier re-aggravated his groin problem, coach Randy Carlyle called it only a "lower-body" injury and said the 25-year-old goaltender had an MRI scheduled.
James Reimer relieved Bernier and stopped 10-of-11 shots he faced against Boston. He's expected to shoulder the load for the rest of the season, beginning Saturday against the Winnipeg Jets, if Bernier is out.
MacIntyre made one appearance in March for the Leafs but has never started an NHL game.
His agent, Thane Campbell, confirmed MacIntyre was returning to Toronto. It was unclear if he'd be back in time for the Leafs' practice Friday morning.
The Marlies were in Utica, N.Y. for a Friday game against the Comets, the Vancouver Canucks' top minor-league affiliate.